We shall: (a) determine whether phosphorylation by cyclic AMP dependent kinases regulates transport of amino acids and calcium in fibroblasts in tissue culture. If so, an identification of the protein(s) whose phosphorylation appears to be involved in transport or its regulation shall be made. (b) We shall attempt to find conditions for the purification and reconstitution of components which on removal from membranes diminish transport rates of Pi and, when added back, enhance transport rates. We shall attempt to determine the possible role these components have in the regulation of Pi transport and perhaps the regulation of transport of other substances. (c) Separation and determination of the transport properties of two populations of plasma membrane vesicles from mouse embryo cells transformed by Simian virus 40 (SV3T3) will be performed. We shall examine the mechanism of regulation of phosphate (Pi) transport by high concentration of phosphate. Also, the relative roles of proton gradients, sodium gradients, and electrical potential on Pi and amino-acid uptake in SV3T3 membrane vesicles and Chinese hamster ovary membrane vesicles will be determined. (d) We shall determine whether growth factors affect membrane potential in the isolated membrane vesicles and whether the factors affect cellular phosphoprotein kinase or phosphoprotein phosphatase activity in vitro.